HDR to Djot Converter
FileFlip converts HDR to Djot entirely inside your browser, using ImageMagick, MuPDF and Pandoc compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert an HDR file to Djot?#
- Drop your HDR file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to Djot and the conversion starts on its own. FileFlip downloads 79.9 MB of WebAssembly the first time and nothing after that, then runs ImageMagick, MuPDF and Pandoc on your own machine.
- Save the Djot file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting HDR to Djot lose quality?#
No. The HDR picture is placed into the Djot document at its full resolution, so every pixel reaches it intact. What you give up is that it becomes a picture inside a document rather than text.
Is it safe to convert HDR files online?#
Yes, because nothing is uploaded. FileFlip converts HDR files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What HDR to Djot actually does to the file#
Converting HDR to Djot runs on ImageMagick, MuPDF and Pandoc, downloads 79.9 MB of WebAssembly the first time and nothing after that, places the picture into the document at full resolution.
| Engine | ImageMagick, MuPDF and Pandoc |
|---|---|
| Conversion path | 3 steps: HDR → PNG → HTML → Djot |
| Downloaded to your browser | 79.9 MB, once, then cached by your browser |
| Quality | Pixels preserved |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
Worth knowing before you start:
- the picture is placed in the document as a picture; no text is recognised out of it
- the file passes through HTML on the way, so anything HTML cannot express does not survive
What is an HDR file?#
An HDR file stores a high-dynamic-range raster image using Radiance's RGBE encoding, which packs red, green and blue mantissas with one shared exponent per pixel so a scene can hold a far wider range of brightness than a standard 8-bit image.
Reach for HDR when you need a compact high-dynamic-range environment map or lighting reference that most 3D tools and renderers can read without a plugin.
Convert HDR to OpenEXR when a VFX pipeline needs true floating-point precision, an alpha channel or multiple layers in one file, or convert it to JPEG or PNG once the image has been tone-mapped for a normal display.
What is a Djot file?#
A DJ file holds a Djot document, a lightweight markup that reads like Markdown but is built on an unambiguous grammar, so it parses the same way in every implementation.
Write in Djot when Markdown's readability is wanted without its parsing ambiguities, and broad tool support isn't a requirement yet.
Convert Djot to another format when sharing with tools or people that only handle Markdown, HTML, or another mainstream format.
HDR to Djot questions people ask#
What is an HDR file used for?
An HDR file most often stores an environment map or lighting reference for 3D rendering, since Radiance's RGBE encoding was built for the Radiance lighting-simulation software. Photographers also use the .hdr extension for panoramas merged from several exposures, before tone-mapping the result down to a normal image.
Is an HDR file the same as an iPhone or camera 'HDR photo'?
No. A phone's HDR mode blends several exposures and saves an ordinary JPEG or HEIC, while an HDR file with the .hdr extension is a Radiance RGBE file that keeps the full brightness range rather than compressing it into 8 bits. The two share a name but not a file format.
What's the difference between HDR and OpenEXR?
HDR (Radiance RGBE) packs each pixel into 32 bits with an 8-bit mantissa per channel and a shared exponent, while OpenEXR stores true 16- or 32-bit floating-point values per channel, supports an alpha channel, and can hold multiple image layers in one file. OpenEXR has mostly replaced HDR in VFX compositing, though HDR remains common for HDRI environment maps because of its smaller size and long-standing tool support.
What is a .dj file?
A .dj file is a Djot document, a lightweight markup language that looks like Markdown but parses under a stricter, unambiguous grammar. It was designed in 2022 by John MacFarlane, who also created Pandoc and co-authored the CommonMark specification.